Although the clinical manifestations of cerebrovascular disease (CVD) typically appear acutely, the deleterious effects of CVD on brain structure and function likely begin in a presymptomatic fashion at a younger age than clinical strokes. In an effort to characterize the prevalence, risk factors, and cognitive correlates of subclinical CVD, the Atherosclerosis Risk in Communities (ARIC) Study (funded by the National Heart, Lung, and Blood Institute) performed cerebral magnetic resonance imaging (MRI) and cognitive assessments on a large, bi-racial sample of middle-aged and young-elderly adults. Results from the ARIC MRI baseline study revealed a remarkably high prevalence of subclinical CVD including silent cerebral infarctions, white matter hyperintensities, and brain atrophy. Moreover, these subclinical abnormalities were found to be associated with reduced cognitive functioning and with clinical CVD outcomes such as incident stroke. Surprisingly little is known about risk factors related to the incidence or progression of subclinical CVD or how progression of these markers may relate to clinical outcomes such as stroke or neurocognitive decline. To address these questions, we propose to perform a follow-up study of the ARIC MRI cohort, repeating semiquantitative MR imaging and cognitive assessments. We will also take advantage of recent advances in MR imaging and obtain volumetric measurements of selected brain regions and expand upon the baseline cognitive assessment to further characterize neurocognitive functioning. The longitudinal design of the proposed study will fill salient gaps in our current understanding of subclinical CVD. Moreover, conducting this study within ARIC takes advantage of ARIC's baseline MRI data, unique African American population, and extensive vascular risk factor data (including new genetic and biochemical factors as well as subclinical markers of both large and small vessel disease), making an efficient study to provide new insights into the incidence, progression, and outcomes associated with subclinical CVD.